1. Field of the Invention
The present invention relates to a data recording and reproducing apparatus for superimposing character data or the like on a material sent out from, for example, an AV server system, and a data recording and reproducing apparatus for managing the present recording and reproducing apparatus and files concerning resources such as devices connected to the present recording and reproducing apparatus.
2. Description of the Prior Art
With the advance of multi-channel data provision due to the spread of the CATV (cable television), demands for simultaneously recording and reproducing a plurality of video and/or audio data (hereafter referred to as AV data) by using a single recording and reproducing apparatus and for reproducing data while recording data unlike conventional VTRs (video tape recorders) are growing intense in recent years. And in order to satisfy the demands, an apparatus called video server (or also called AV (Audio and Video) server) which records and reproduces AV data by using a random accessible recording medium such as a hard disk is spreading.
In general, each of AV servers in broadcast stations must have a large capacity because the needed data transfer rate is high and data of a long time must be recorded because of demands on the picture quality and sound quality. Therefore, there have been made an attempt to increase the data transfer rate and the capacity by using a plurality of hard disks hereafter referred to as HDs) capable of storing AV data and conducting parallel processing, and an attempt to secure the reliability even if any HD device should fail, by recording parity data.
Even in the case where demanded numbers of channels are different according to the contents of programs provided by broadcasting stations and broadcast forms, material data including a plurality of AV data are recorded distributively, a large number of channels are sent out simultaneously, and the same material data are reproduced in a multichannel form with staggered reproduction times. By doing so, systems such as VOD (video on demand) and NVOD (near video on demand) are constructed. Thus, a multi-channel AV server capable of coping with a wide variety of use forms can be implemented.
In the HD apparatus used in such an AV server, there is used an RAID (Redundant Arrays of Inexpensive Disks) technique advocated in Patterson, “A case for Redundant Arrays of Inexpensive Disks (RAID)”, ACM SIGMOND Conference, Chicago, Ill, Jun. 1-3, 1988. In the RAID technique, a plurality of hard disk drives (hereafter referred to “HDD”) each formed of a plurality of HDs are arranged.
In the aforementioned paper, RAIDs are classified into five categories, RAID-1 to RAID-5. RAID-1 is a scheme in which the same content is written in two HDDs. RAID-3 is a scheme in which input data is divided into fixed lengths and recorded on a plurality of HDDs, and parity data which is exclusive OR of mutually associated data blocks of each HDD is generated and written into another HDD. RAID-5 is a scheme in which the unit (block) of data division is made larger and one divisional data is recorded in one HDD as a data block, and in addition a result (parity data) obtained by deriving an exclusive OR of mutually associated data blocks of each HDD is recorded in other HDDs and the parity block is distributed among other blocks.
As for other RAIDS, see the aforementioned paper.
If any HD fails and the HD is replaced by a new HD in an HD apparatus (hereafter simply referred to as “RAID”) using this RAID technique, it is possible to restore data on the failed HD by using data and parity data reproduced from HDs, recording the restored data in the new HD, and thereby rebuild or reconstruct the data on the failed HD.
For conducting simultaneous recording and reproducing of a plurality of AV data, it is necessary to conduct AV data inputting and outputting simultaneously in a plurality of channels. In the AV server, therefore, there are provided a plurality of input/output ports which operate independently of each other, and one input port and one output port inputs and outputs data corresponding to one channel.
If input/output ports conduct transfer of AV data with the RAID completely at the same time, then those AV data flow simultaneously on a bus connecting input/output ports to RAIDs in the AV server, and it becomes impossible to process the AV data. Therefore, time slots (=time intervals) for which use of the bus is permitted are assigned to input/output ports in order, and each input/output port conducts transfer of AV data with an RAID via the bus in only the assigned time slot. Strictly speaking, therefore, a plurality of AV data are not recorded and reproduced simultaneously. When viewed in the context of a time span longer than a time slot, however, it can be said that the simultaneous recording and reproducing of a plurality of AV data are accomplished.
In an AV server system formed in a broadcasting station by using such an AV server as the nucleus, in general, files describing types and parameters of individual resources hardware resources such as HDDs and input/output ports and software resources) of the AV server are managed in the form of a database.
As for advantages of sending out of a material by using this AV server in a broadcasting station, there can be mentioned an advantage that sending of a recorded material can be started quickly because reproducing can be made while conducting reproducing, and an advantage that the order of sending of recorded materials can be altered arbitrarily because random access is possible.
By the way, when sending out a material in a broadcasting station, it is widely conducted to superimpose character data or the like on the material. For example, in a music program, character data representing a title of a musical composition and/or an artist name are superimposed on a video image of the artist.
Conventionally, for conducting such superimposition in a broadcasting station, at an editing stage before starting the send-out, a superimposed material is produced by combining the character data or the like with the material and the superimposed material is recorded.
However, with such a conventional superimposing method, the number of man-hours is large. Accordingly, the cost and labor are substantially increased.
In such a conventional superimposing method, however, the number of man-hours is large and consequently it takes a long time until it becomes possible to send the superimposed material. If the conventional superimposing method is adopted when sending out a material by using the AV server, therefore, then the advantage of the AV server that sending of the recorded material can be started quickly cannot be made the most of.
Furthermore, when the order of sending out materials is altered in the middle of superimposing according to a specified order of sending out materials, it is difficult to cope with this flexibly in the conventional superimposing method. If the conventional superimposing method is adopted when sending out materials by utilizing the AV server, then the advantage of the AV server that the order of sending out recorded materials can be altered arbitrarily cannot be made the most of.
Furthermore, the above described conventional AV server system in the broadcasting station has the following disadvantages.
(a) There are a large number of resources in the AV server. (For example, there are approximately 300 resources in a certain AV server.) Therefore, it is difficult to grasp the entire structure of the AV server from the files describing the types and parameters of a large number of resources. Also in the case where a fault occurs in any resource, it is difficult to determine from these files which position the resource assumes in the entire AV server. Therefore, it takes a long time to grasp the fault and cope with the fault.
(b) Operation for rebuilding differs according to whether the type of the RAID is SCSI or SBX. At the time of rebuilding, it is necessary to determine which type of RAIDs the AV server of the AV server system has and then conduct operation corresponding to the type. In addition, operation for the SCSI type is writing a sequence for each system by using an application tool (such as LightChk. exe), and its operation is troublesome. On the other hand, as for operation for an RAID of the SBX type, a personnel of maintenance service interrupts the system running and conducts the operation by using a dedicated tool, and the operation cannot be conducted during the system running. A user (i.e., a user of the AV server system in a broadcasting station) cannot conduct the operation.